Contact lenses trace their history as far back as 1508, when Leonardo da Vinci described in his writings a method of directly altering corneal power by submerging the eye in a bowl of water. René Descartes proposed a related idea in 1636 which involved the placement of a glass tube filled with liquid in direct contact with the cornea. The first wearable contact lenses were created by German physiologist Adolf Eugen Fick and German medical student F. E. Muller in 1887. Further advances came in 1950, when Oregon optometrist Dr. George Butterfield created a corneal lens designed such that the inner surface of the lens was complimentary to the eye's shape, rather than flat.
Contact lenses finally came into widespread use by consumers in the 1960s with the development of soft, water absorbing (“hydrogel”) polymers for contact lenses. Other significant developments in the field followed, include the advent of oxygen permeable lenses in the late 1970s, the development of extended wear contact lenses (which became available to consumers in 1981), and the introduction in 1995 of daily disposable contact lenses. At present, it is estimated that 125 million people use contact lenses worldwide (about 2% of the world's population), which includes some 28 to 38 million users in the United States alone.
While contact lenses offer several clear advantages over prescription glasses and other corrective vision measures currently known to the art, multiple use contact lenses require a certain amount of maintenance in order to function optimally and to remain comfortable during use. In particular, such contact lenses require periodic treatment for the removal of protein deposits and debris from the surfaces of the lenses, and also typically require periodic disinfection of the lenses. In the absence of such maintenance, the user's experience with the lenses typically begins to degrade, both in terms of the quality of vision provided by the lenses and the degree of comfort associated with wearing them. Failure to sanitize the lenses periodically may also result in potentially serious infections of the eyes and surrounding tissues.
Various methods have been developed in the art for the periodic treatment and disinfection of contact lenses. One common approach requires the user to remove the lenses periodically and to treat them with enzyme tablets that are dissolved in a liquid medium. The enzyme tablets are designed to remove or dislodge protein deposits and debris from the surfaces of the lenses. The enzyme tablets are typically designed to be dissolved in a 2% hydrogen peroxide solution, which has the further benefit of disinfecting the lenses while they are being cleaned.
In another approach known to the art for treating contact lenses, the lenses are disposed in a liquid medium and are exposed to subsonic frequencies, which act to dislodge protein deposits and other debris from the surfaces of the lenses. The liquid medium is then disinfected through prolonged exposure (e.g., for 15 minutes or more) to UV radiation and heat, which thus disinfects the lenses indirectly. In this approach, the cleaning device is typically designed so that the contact lenses being treated will not be directly exposed to the UV light source, since prolonged, direct exposure of the lenses to the UV light source for the time required for disinfection can damage the lenses.
Regardless of the methodology employed to treat and disinfect multiple use contact lenses, the cost and inconvenience of these procedures to the end user is significant. It is thus desirable to minimize the frequency of these treatments to the extent possible.
At present, the frequency of such treatments is often prescribed by the contact lens manufacturer, and may be based on statistical averages which may be derived, for example, from clinical studies or laboratory tests. For some users, the frequency of such treatments may be too great, and may thus represent an unnecessary cost and inconvenience. For other users, the frequency of these treatments may actually be too small. For still other users, the optimal frequency of treatment may change over time, and may depend on such factors as environmental conditions, physiological factors, health, and other such considerations.
A further problem facing wearers of contact lenses concerns damage to the lenses. As with any other article of manufacture, a certain percentage of contact lenses sold to consumers contain manufacturing defects. Such defects can adversely affect the ability of the lenses to function correctly or to sit properly upon the eye of the user, and may also cause discomfort to the user. Such defects may include scratches, tears, holes, peripheral damage, and wrinkles or bumps in the material of the lens, and may also include the presence of soil, debris or other foreign matter on the surfaces of the lens.
These defects may also result from handling of the lenses by the user. For example, some extended wear contact lenses require the user to clean the lenses daily or between uses. In many cases, this requires the user to manually apply a cleaning solution to the lenses. Although lenses for which this type of treatment is prescribed are typically designed to be sufficiently durable to withstand such treatment, they may be damaged by the process nonetheless. Such damage may result from unapparent weaknesses in the lens material, from failure by the user to follow proper procedures, or from the presence of contaminants on the lenses or on the user's hands at the time of cleaning.
This type of problem has existed in the art for some time, and various attempts have been made to address it. For example, U.S. Pat. No. 4,545,479 (Figari) and U.S. Pat. No. 4,784,258 (Figari) propose a contact lens carrying case which is equipped with a magnifying lens assembly and a light source, and which is designed to allow the user to visibly inspect lenses disposed within the carrying case for defects. U.S. Pat. No. 4,623,249 (Grant), U.S. Pat. No. 5,099,987 (Bieri), U.S. Pat. No. 5,337,888 (Morrison), and U.S. Pat. No. 6,092,646 (Glazier) disclose other contact lens carrying cases that also allow the user to inspect lenses disposed within the case. U.S. Pat. No. 5,440,458 (Volk) is also of interest in that it discloses an illuminated lens case for containing a plurality of lenses used in diagnostic procedures in darkened rooms, although the reference does not mention the use of the case disclosed therein in conjunction with contact lenses. U.S. Pat. No. 6,134,342 (Doke et al.) and U.S. Pat. No. 6,259,518 (Russell et al.) describe methods for examining lenses for defects at the manufacturing level.
While the foregoing devices and processes may be suitable for some purposes, in practice, these devices do not provide a clear indication of many of the types of defects that may be present in contact lenses, nor do these devices provide a satisfactory means for clearly viewing many of the types of deposits or debris that may be present on the surfaces of the lenses. There is thus a need in the art for a device that enables consumers to visually inspect the surfaces of contact lenses for the presence of defects, deposits or impurities. In particular, there is a need in the art for such a device that enables consumers to easily and conveniently gauge whether the lenses require cleaning, or need to be disposed of. There is further a need in the art for such a device which may be used to tailor cleaning of the lenses to such times when cleaning is actually required. These and other needs are met by the devices and methodologies disclosed herein and hereinafter described.